/*
 * Copyright 1999-2017 Alibaba Group Holding Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package studio.raptor.sqlparser.ast.statement;

import studio.raptor.sqlparser.ast.SQLExpr;
import studio.raptor.sqlparser.ast.SQLObjectImpl;
import studio.raptor.sqlparser.visitor.SQLASTVisitor;

public class SQLSelectItem extends SQLObjectImpl {

  protected SQLExpr expr;
  protected String alias;
  protected boolean connectByRoot = false;

  public SQLSelectItem() {

  }

  public SQLSelectItem(SQLExpr expr) {
    this(expr, null);
  }

  public SQLSelectItem(SQLExpr expr, String alias) {
    this.expr = expr;
    this.alias = alias;

    if (expr != null) {
      expr.setParent(this);
    }
  }

  public SQLSelectItem(SQLExpr expr, String alias, boolean connectByRoot) {
    this.connectByRoot = connectByRoot;
    this.expr = expr;
    this.alias = alias;

    if (expr != null) {
      expr.setParent(this);
    }
  }

  public SQLExpr getExpr() {
    return this.expr;
  }

  public void setExpr(SQLExpr expr) {
    this.expr = expr;
    if (expr != null) {
      expr.setParent(this);
    }
  }

  public String getAlias() {
    return this.alias;
  }

  public void setAlias(String alias) {
    this.alias = alias;
  }

  public void output(StringBuffer buf) {
    if (this.connectByRoot) {
      buf.append(" CONNECT_BY_ROOT ");
    }
    this.expr.output(buf);
    if ((this.alias != null) && (this.alias.length() != 0)) {
      buf.append(" AS ");
      buf.append(this.alias);
    }
  }

  protected void accept0(SQLASTVisitor visitor) {
    if (visitor.visit(this)) {
      acceptChild(visitor, this.expr);
    }
    visitor.endVisit(this);
  }

  @Override
  public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((alias == null) ? 0 : alias.hashCode());
    result = prime * result + ((expr == null) ? 0 : expr.hashCode());
    return result;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (obj == null) {
      return false;
    }
    if (getClass() != obj.getClass()) {
      return false;
    }
    SQLSelectItem other = (SQLSelectItem) obj;
    if (alias == null) {
      if (other.alias != null) {
        return false;
      }
    } else if (!alias.equals(other.alias)) {
      return false;
    }
    if (expr == null) {
      if (other.expr != null) {
        return false;
      }
    } else if (!expr.equals(other.expr)) {
      return false;
    }
    return true;
  }

  public boolean isConnectByRoot() {
    return connectByRoot;
  }

  public void setConnectByRoot(boolean connectByRoot) {
    this.connectByRoot = connectByRoot;
  }

}
